A new method of orthoesterification, under kinetic control, at non-anomeric positions. Application to the d-glucose and d-mannose series and selective hydrolysis of the corresponding orthoesters

Bouchra, M.; Calinaud, Pierre; Gelas, Jacques

doi:10.1016/0008-6215(94)00306-z

Cited by 30 publications

(9 citation statements)

References 21 publications

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“…Treatment of ethyl 4,6-di-O-acetyl-1-thio-a-D-mannopyranoside (2) 18 with triethyl orthoacetate in the presence of p-toluenesulfonic acid 19 followed by acidic hydrolysis of the orthoacetate derivative furnished ethyl 2,4,6-tri-O-acetyl-1-thioa-D-mannopyranoside (3) in 79% yield. Ethyl (2,3-di-O-benzyl-4,6-O-benzylidene-a-D-glucopyranosyl)-(1/4)-2,3,6-tri-O-benzyl-1-thio-b-D-glucopyranoside (4), 20 prepared from D-maltose, was treated with acetic anhydride 21 in the presence of perchloric acid supported over silica gel (HClO 4 /SiO 2 ) 22 to furnish ethyl (4,6-di-O-acetyl-2,3-di-O-benzyl-a-D-glucopyranosyl)-(1/4)-2,3,6-tri-O-benzyl-1-thio-b-D-glucopyranoside (5) in 80% yield (Scheme 1).…”

Section: Resultsmentioning

confidence: 99%

Synthesis of the pentasaccharide repeating unit of the O-antigen of Escherichia coli O175 using one-pot glycosylations and its conformational analysis

Ghosh¹,

Kar²,

Bhunia³

et al. 2014

Tetrahedron

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Section: Resultsmentioning

confidence: 99%

Synthesis of the pentasaccharide repeating unit of the O-antigen of Escherichia coli O175 using one-pot glycosylations and its conformational analysis

Ghosh¹,

Kar²,

Bhunia³

et al. 2014

Tetrahedron

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“…Moreover, this method provided the key intermediate 7 which was used to synthesize the selectively protected derivatives 9 and 10 which can be further glycosylated on C-3 or C-4 of the arabinose residue. To synthesize 4-methoxybenzyl 2,3,4-tri-O-benzoyl-D-L-rhamnopyranosyl-(1o2)-4-O-acetyl-E-Larabinopyranoside (9), which was monoacetylated at the axial hydroxyl group on C-4 of arabinose, compound 7 was treated with triethyl orthoacetate (CH 3 C(OEt) 3 ) and ptoluenesulfonic acid as an acid catalyst in toluene and the intermediate cyclic ortho ester was subsequently cleaved under acidic conditions (80% aqueous acetic acid) to afford 7 at a good yield (95%, over two steps, Bouchra et al, 1995;Hanessian and Roy, 1985). The structure of 9 was unambiguously confirmed by 400 MHz 1 H-NMR spectroscopy with a singlet peak of acetyl at G 2.17.…”

Section: Resultsmentioning

confidence: 99%

A convenient preparation of a disaccharide motif and its role in the cytotoxicity of the triterpenoid saponin, α-hederin

et al. 2008

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The sugar structures of triterpenoid saponins, such as alpha-hederin, are intimately associated with their antitumor activities and other biological activities. The alpha-L: -rhamnopyranosyl-(1-->2)-alpha-L: -arabinopyranoside group of alpha-hederin alters the cytotoxicity of its aglycon, hederagenin. This study explored the role of this saccharide unit in the cytotoxic effect of alpha-hederin and the possibility of its use as a carrier moiety in prodrugs of anticancer agents. A new convenient and practical procedure for the preparation of 4-methoxybenzoyl-2,3,4-tri-O-benzoyl-alpha-L: -rhamnopyranosyl-(1-->2)-3,4-O-dibenzoyl-beta-L: -arabinopyranoside (2) from 4-methoxybenzoyl-beta-L: -arabinopyranoside was accomplished using four steps with an overall yield of 63%. The use of BF(3)-OEt(2) as a catalyst in the glycosylation step in this procedure had a large advantage over the TMSOTf catalyst used in the usual method. Moreover, the key intermediate obtained in this procedure, 4-methoxybenzoyl-2,3,4-tri-O-benzoyl-alpha-L: -rhamnopyranosyl-(1-->2)-alpha-L: -arabinopyranoside (7), was selectively transformed to 4-methoxybenzoyl-2,3,4-tri-O-benzoyl-alpha-L: -rhamnopyranosyl-(1-->2)-4-O-acetyl-alpha-L: -arabinopyranoside (9) and 4-methoxybenzoyl-2,3,4-tri-O-benzoyl-alpha-L: -rhamnopyranosyl-(1-->2)-3-O-benzoyl-beta-L: -arabinopyranoside (10). These derivatives did not show any cytotoxicity against human cancer cell lines. Thus the 3-O-alpha-L: -rhamnopyranosyl-(1-->2)-alpha-L: -arabinopyranoside could be used as a nontoxic carrier moiety to enhance the activity of anticancer drugs.

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“…Selective acetylation of compound 7 by the formation of an orthoester intermediate [38] resulted in the formation of 2-azidoethyl 2,4,6-tri- O -acetyl-β-D-galactopyranoside ( 2 ) in 74% yield (Scheme 1). …”

Section: Resultsmentioning

confidence: 99%

Convergent synthesis of a tetrasaccharide repeating unit of the O-specific polysaccharide from the cell wall lipopolysaccharide of Azospirillum brasilense strain Sp7

Mandal¹,

Dhara²,

Misra³

2014

Beilstein J. Org. Chem.

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A new method of orthoesterification, under kinetic control, at non-anomeric positions. Application to the d-glucose and d-mannose series and selective hydrolysis of the corresponding orthoesters

Cited by 30 publications

References 21 publications

Synthesis of the pentasaccharide repeating unit of the O-antigen of Escherichia coli O175 using one-pot glycosylations and its conformational analysis

Synthesis of the pentasaccharide repeating unit of the O-antigen of Escherichia coli O175 using one-pot glycosylations and its conformational analysis

A convenient preparation of a disaccharide motif and its role in the cytotoxicity of the triterpenoid saponin, α-hederin

Convergent synthesis of a tetrasaccharide repeating unit of the O-specific polysaccharide from the cell wall lipopolysaccharide of Azospirillum brasilense strain Sp7

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